The Full-sib mated sixth (SBF6) generation of intergeneric population of papaya from the cross CP 50 x Vasconcellea cauliflora was evaluated to select the progenies with PRSV tolerance coupled with better yield. In order to identify the well performing progenies, the mean performance and genetic parameters were estimated. Interestingly, the results of the variability study revealed that the genotypic coefficient of variation on number of fruits, leaf area and number of leaves were higher and making it as the selectable traits. The correlation analysis was made to understand the degree of relationship between the PRSV tolerance and various morphological traits. The result showed that plant height and number of fruits were significantly and negatively correlated with per cent disease index (PDI) with the r value of -0.273 and -0.261 respectively. By considering the number of fruits as the selectable trait, a ranking model system was developed and the results showed 5 ranks of 53 progenies. Among them, 13 well performing progenies from Rank IV and Rank V were selected for further evaluation. The ranking model system helps the researchers by making the selection process statistically much easier and efficient.

Research was conducted at the University Orchard, Horticultural College and Research Institute, to investigate the extent of pollen production, pollen fertility, fruit set, fruit growth and seed set as well as seedling vigour when two wild relatives of papaya (Vasconcellea cauliflora and Vasconcellea candamarcensis) are involved in the hybridization programme as male parents with three papaya cultivars (CO 7, TNAU Papaya CO 8 and Pusa Nanha) as female parents. Among the two wild relatives, V. candamarcensis was more polleniferous but with significantly lesser pollen viability and germination than V. cauliflora. Among the six intergeneric crosses, although the fruit set ranged from 60.00% to 93.33% the fruit retention till harvest was only 30.77 per cent to 35.71 per cent. The study also revealed metaxenic influence of wild parent on the growth of the fruits derived after crossing. Seed set was observed only with CO 7 as female parent but the seed size and weight, germination and seedling vigour recorded by intergeneric crosses of CO 7 with Vasconcellea were found to be low. The implications of the observations are discussed in relevance to employing the wild relatives for improvement of papaya.